kvm: avoid uninitialized-variable warnings

When PAGE_OFFSET is not a compile-time constant, we run into
warnings from the use of kvm_is_error_hva() that the compiler
cannot optimize out:

arch/arm/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_gfn_to_hva_cache_init':
arch/arm/kvm/../../../virt/kvm/kvm_main.c:1978:14: error: 'nr_pages_avail' may be used uninitialized in this function [-Werror=maybe-uninitialized]
arch/arm/kvm/../../../virt/kvm/kvm_main.c: In function 'gfn_to_page_many_atomic':
arch/arm/kvm/../../../virt/kvm/kvm_main.c:1660:5: error: 'entry' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This adds fake initializations to the two instances I ran into.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

virt/kvm/kvm_main.c

@@ -1651,7 +1651,7 @@ int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
 			    struct page **pages, int nr_pages)
 {
 	unsigned long addr;
-	gfn_t entry;
+	gfn_t entry = 0;
 
 	addr = gfn_to_hva_many(slot, gfn, &entry);
 	if (kvm_is_error_hva(addr))
@@ -1970,6 +1970,7 @@ static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots,
 		 * verify that the entire region is valid here.
 		 */
 		while (start_gfn <= end_gfn) {
+			nr_pages_avail = 0;
 			ghc->memslot = __gfn_to_memslot(slots, start_gfn);
 			ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
 						   &nr_pages_avail);